dpinst silent signed driver installation fails on windows 7

Trying to install my driver silently through dpinst (with /q) fails on windows 7 but works on both 8.1 and 10. The driver is signed and I have added my certificate to the trusted publishers list.

This is the approach recommended here and in various other articles ive found. dpinst / DifX won't install signed driver silently

In non-silent mode dpinst gives a prompt to trust the publisher and install the driver. In silent mode it refuses to install and gives this error.

     sig:                Success: File is signed in Authenticode(tm) catalog.
     sig:                Error 0xe0000242: The publisher of an Authenticode(tm) signed catalog has not yet been established as trusted.
     sig:           {_VERIFY_FILE_SIGNATURE exit(0xe0000242)} 10:23:15.260
!!!  sto:           Driver package signer is unknown. Assuming untrusted signer. Error = 0x800F0242
!!!  ndv:           Driver package failed signature validation. Error = 0xE0000242
     sto:      {DRIVERSTORE_IMPORT_NOTIFY_VALIDATE exit(0xe0000242)} 10:23:15.260

This is extracted from setupapi.dev.log

Is this still the correct process or has something changed recently?

Additional info: all testing done on 64bit, certificate is normal code signing one not EV, im signing with the right cross certificate, my cert is SHA256 but ive got the patch on windows to support that.

Might be a little late, but which patch(s) have you installed? KB3033929 is the required patch for sha256 on Windows 7 and Windows Server 2008 R2. An additional problem I ran into, is even though I had installed my certificate as a trusted publisher, the installation was ignoring it. I would always get prompted to trust the publisher. To fix this issue there is an additional hotfix kb2921916. Hopefully this helps you or someone else out there.